Sat27November0556PM 47

Which of the following is correct in malignant hyperpyrexia?

(Please select 1 option)

Elevation of serum creatine kinase and myoglobinuria is diagnostic Incorrect answer selected

The only available specific treatment is sodium dantrolene, which has a neutral pH

The predisposing gene is thought to be on chromosome 9

A mortality rate of 20% may be expected

Muscle biopsy may be histologically normal This is the correct answer

Explanation

Malignant hyperpyrexia (MH) is characterised by increased temperature and muscle rigidity during anaesthesia, which results from abnormal skeletal muscle contraction and increased metabolism.

The predisposing gene is thought to be on chromosome 19, close to the gene for the ryanodine/dihydropyridine receptor complex.

Known triggering agents include the volatile anaesthetic agents and suxamethonium. Patients show different sensitivity to the triggering agents and the reaction can be delayed by several hours.

Intravenous dantrolene (up to 10 mg/kg) is the only available specific treatment and care must be taken when administering as the solution has a pH of 9-10.

The prognosis of malignant hyperpyrexia is good when the appropriate treatment is instigated early, mortality being less than 5% (prior to dantrolene the mortality was 80%).

Serum creatine kinase elevation and myoglobinuria are suggestive but not diagnostic of MH. Myoglobin and creatine kinase are both known to increase after giving suxamethonium to normal patients.

Contracture tests using caffeine and halothane are the investigations of choice.

Muscle biopsies may appear histologically normal.

Answer Statistics

1

6%

2

20%

3

18%

4

12%

5

45%

Times answered: 257